During engine operation, unburned fuel and exhaust gas escape from the combustion chamber, past the piston rings, and enter the crankcase. Over time, the unburned fuel and exhaust gas condense and dilute the engine oil in the crankcase, which reduces the ability of the engine oil to lubricate the engine. In order to reduce dilution of the engine oil, an engine of a rail vehicle typically includes a ventilation system to draw in fresh air and expel unburned fuel and exhaust gas from the crankcase.
In one example, a vehicle includes an engine having a crankcase that is vented through a hose to a coalescer that filters the vented gas. For example, the coalescer includes steel wool that facilitates condensation of oil droplets in the gas stream. The condensed oil droplets are returned from the coalescer to the crankcase by a return line. Furthermore, an eductor tube is connected between the coalescer and an exhaust muffler. As gas flowing from the coalescer streams through the eductor tube, a pressure differential is created to generate vacuum for crankcase venting.
The inventors herein have recognized some issues in such systems. For example, any particulate matter in the gas stream vented from the crankcase that escapes filtration by the coalescer is drawn into the exhaust stream and exits the exhaust stack. In other words, the particulate matter vented from the crankcase that is not filtered by the coalescer contributes to emissions of the vehicle.